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[This corrects the article DOI: 10.1038/s42003-018-0120-9.].

Most plants engage in symbioses with mycorrhizal fungi in soils and net consequences for plants vary widely from mutualism to parasitism. However, we lack a synthetic understanding of the evolutionary and ecological forces driving such variation for this or any other nutritional symbiosis. We used meta-analysis across 646 combinations of plants and fungi to show that evolutionary history explains substantially more variation in plant responses to mycorrhizal fungi than the ecological factors included in this study, such as nutrient fertilization and additional microbes. Evolutionary history also has a different influence on outcomes of ectomycorrhizal versus arbuscular mycorrhizal symbioses; the former are best explained by the multiple evolutionary origins of ectomycorrhizal lifestyle in plants, while the latter are best explained by recent diversification in plants; both are also explained by evolution of specificity between plants and fungi. These results provide the foundation for a synthetic framework to predict the outcomes of nutritional mutualisms., Competing Interests: The authors declare no competing interests.

Unlabelled: Arbuscular mycorrhizal (AM) fungi form mutualisms with plant roots that increase plant growth and shape plant communities. Each AM fungal cell contains a large amount of genetic diversity, but it is unclear if this diversity varies across evolutionary lineages. We found that sequence variation in the nuclear large-subunit (LSU) rRNA gene from 29 isolates representing 21 AM fungal species generally assorted into genus- and species-level clades, with the exception of species of the genera Claroideoglomus and Entrophospora However, there were significant differences in the levels of sequence variation across the phylogeny and between genera, indicating that it is an evolutionarily constrained trait in AM fungi. These consistent patterns of sequence variation across both phylogenetic and taxonomic groups pose challenges to interpreting operational taxonomic units (OTUs) as approximations of species-level groups of AM fungi. We demonstrate that the OTUs produced by five sequence clustering methods using 97% or equivalent sequence similarity thresholds failed to match the expected species of AM fungi, although OTUs from AbundantOTU, CD-HIT-OTU, and CROP corresponded better to species than did OTUs from mothur or UPARSE. This lack of OTU-to-species correspondence resulted both from sequences of one species being split into multiple OTUs and from sequences of multiple species being lumped into the same OTU. The OTU richness therefore will not reliably correspond to the AM fungal species richness in environmental samples. Conservatively, this error can overestimate species richness by 4-fold or underestimate richness by one-half, and the direction of this error will depend on the genera represented in the sample., Importance: Arbuscular mycorrhizal (AM) fungi form important mutualisms with the roots of most plant species. Individual AM fungi are genetically diverse, but it is unclear whether the level of this diversity differs among evolutionary lineages. We found that the amount of sequence variation in an rRNA gene that is commonly used to identify AM fungal species varied significantly between evolutionary groups that correspond to different genera, with the exception of two genera that are genetically indistinguishable from each other. When we clustered groups of similar sequences into operational taxonomic units (OTUs) using five different clustering methods, these patterns of sequence variation caused the number of OTUs to either over- or underestimate the actual number of AM fungal species, depending on the genus. Our results indicate that OTU-based inferences about AM fungal species composition from environmental sequences can be improved if they take these taxonomically structured patterns of sequence variation into account., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Plants form belowground associations with mycorrhizal fungi in one of the most common symbioses on Earth. However, few large-scale generalizations exist for the structure and function of mycorrhizal symbioses, as the nature of this relationship varies from mutualistic to parasitic and is largely context-dependent. We announce the public release of MycoDB, a database of 4,010 studies (from 438 unique publications) to aid in multi-factor meta-analyses elucidating the ecological and evolutionary context in which mycorrhizal fungi alter plant productivity. Over 10 years with nearly 80 collaborators, we compiled data on the response of plant biomass to mycorrhizal fungal inoculation, including meta-analysis metrics and 24 additional explanatory variables that describe the biotic and abiotic context of each study. We also include phylogenetic trees for all plants and fungi in the database. To our knowledge, MycoDB is the largest ecological meta-analysis database. We aim to share these data to highlight significant gaps in mycorrhizal research and encourage synthesis to explore the ecological and evolutionary generalities that govern mycorrhizal functioning in ecosystems.

Periglandula ipomoeae and P. turbinae (Ascomycota, Clavicipitaceae) are recently described fungi that form symbiotic associations with the morning glories (Convolvulaceae) Ipomoea asarifolia and Turbina corymbosa, respectively. These Periglandula species are vertically transmitted and produce bioactive ergot alkaloids in seeds of infected plants and ephemeral mycelia on the adaxial surface of young leaves. Whether other morning glories that contain ergot alkaloids also are infected by Periglandula fungi is a central question. Here we report on a survey of eight species of Convolvulaceae (Argyreia nervosa, I. amnicola, I. argillicola, I. gracilis, I. hildebrandtii, I. leptophylla, I. muelleri, I. pes-caprae) for ergot alkaloids in seeds and associated clavicipitaceous fungi potentially responsible for their production. All host species contained ergot alkaloids in four distinct chemotypes with concentrations of 15.8-3223.0 μg/g. Each chemotype was a combination of four or five ergot alkaloids out of seven alkaloids detected across all hosts. In addition, each host species exhibited characteristic epiphytic mycelia on adaxial surfaces of young leaves with considerable interspecific differences in mycelial density. We sequenced three loci from fungi infecting each host: the nuclear rDNA internal transcribed spacer region (ITS), introns of the translation factor 1-α gene (tefA) and the dimethylallyl-tryptophan synthase gene (dmaW), which codes for the enzyme that catalyzes the first step in ergot alkaloid biosynthesis. Phylogenetic analyses confirmed that these fungi are in the family Clavicipitaceae and form a monophyletic group with the two described Periglandula species. This study is the first to report Periglandula spp. from Asian, Australian, African and North American species of Convolvulaceae, including host species with a shrub growth form and host species occurring outside of the tropics. This study demonstrates that ergot alkaloids in morning glories always co-occur with Periglandula spp. and that closely related Periglandula spp. produce alkaloid chemotypes more similar than more distantly related species., (© 2015 by The Mycological Society of America.)

• Soil aggregate stability is an important ecosystem property that is altered by anthropogenic disturbance. Yet, the generalization of these alterations and the identification of the main contributors are limited by the absence of cross-site comparisons and the application of inconsistent methodologies across regions. • We assessed aggregate stability in paired remnant and post-disturbance grasslands across California, shortgrass and tallgrass prairies, and in manipulative experiments of plant composition and soil microbial inoculation. • Grasslands recovering from anthropogenic disturbance consistently had lower aggregate stability than remnants. Across all grasslands, non-native plant diversity was significantly associated with reduced soil aggregate stability. A negative effect of non-native plants on aggregate stability was also observed in a mesocosm experiment comparing native and non-native plants from California grasslands. Moreover, an inoculation study demonstrated that the degradation of the microbial community also contributes to the decline in soil aggregate stability in disturbed grasslands. • Anthropogenic disturbance consistently reduced water-stable aggregates. The stability of aggregates was reduced by non-native plants and the degradation of the native soil microbial community. This latter effect might contribute to the sustained decline in aggregate stability following anthropogenic disturbance. Further exploration is advocated to understand the generality of these potential mechanisms., (© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.)